The 33 Hottest New Workout Classes in the U.S.

What to expect: A unique indoor cycling strategy—superfast pacing and push-ups off the handlebars to the beat of bass-thumping music. Diehards liken it to "dancing on a bike." Just when you think you can't pedal another second, catch your breath with a bout of hammer curls and shoulder presses in the saddle using 2-pound hand weights. You may also notice familiar faces in your row. No biggie; it's probably only regulars Katie Holmes and Jake Gyllenhaal.

Know before you go: Forgot your hair tie, deodorant or even gum? This studio keeps all on hand for free.

Your turn: Steal Soul's mojo: Go to its site to download 10 of the most popular leg-churning songs played in class that month.

We polled more than 100 gyms and studios in four trend-setting cities (New York, Miami, L.A. and Chicago) for their hottest classes (including Zumba!). Not in those ZIP codes? Get better-body benefits wherever you are with our insider tips.